Kazmi was arraigned on Wednesday at the court of Chief Metropolitan Magistrate Vinod Yadav and remanded to police custody of 20 days, the Times of India reported.

Delhi police say Kazmi was not directly involved in the blast, but played an integral role in the conspiracy and could lead them to the bike-borne men who planted a magnetic bomb on the car of Tal Yehoshua Koren, wife of Israel's defense attaché in Delhi.

Yehoshua-Koren and her driver were among the four people injured in the blast, which Israeli prime minister Binyamin Netanyahu squarely blames on Iran and Hizbullah.

The Delhi bombing occurred on the same day as the averted bombing of an Israeli embassy car in Tbilisi, Georgia. The next day, on February 14, a botched bombing attempt by a group of Iranian nationals occurred in Bangkok.

Thai police, who have arrested three of the bombers, say Israeli diplomats were the target.

Magistrate Vinod Yadav remanded Kazmi to police custody until 27 March to facilitate further custodial interrogation by Special Cell officers investigating the case. The officers cited the possibility of “foreign involvement” in the case as the principal reason for an extended remand.

Officers told the court that the attack was launched in a well-planned manner and was not an accident, but refused to share any more details saying the main suspects might flee if information about the investigation was disclosed to the public.

Kazmi's attorney, Vijay Aggarwal, opposed the application for his police custody saying the police ignored accepted procedures in their arrest of Kazmi.

“The court cannot send him to police custody unless they have a proper case diary and even the arrest is illegal as the men who arrested him were in plain clothes, which is in violation of the guidelines of the Supreme Court,” he said.

He also charged police were branding Kazmi as an "international terrorist" when he is really a journalist who had covered the Iraq war and also covers issues related to Iran.

The court did not accept Aggarwal’s arguments and sided with prosecutors who citied “exigent circumstances.”

Police sources told the Hindustan Times that Kazmi helped the suspects in reconnoitering the Israeli embassy and keeping tabs on arrival and departures of the diplomats.

Shortly after the attack, the Times of India quoted sources close to investigators as saying they believe Iran had carried out the 13 February attack by proxy. Indian officials have also said there will be "consequences" if Iran is implicated in the attack.

However, police and government officials in India – which has some USD 12 billion in annual trade with Iran on the line – have refused to publicly comment on Iran's possible involvement.

“The investigations are going on; we will inform the media on further leads when we have some,” Delhi Police Commissioner BK Gupta said when reporters directly asked him about Iranian links in the case.

“The investigations are pursuing various leads...and our understanding is that no conclusions can be drawn at this stage,” official spokesperson of the Ministry of External Affairs, Syed Akbaruddin, said in New Delhi.